A method for subnanosecond pulse measurements ofI‐Vcharacteristics is described. The sample is mounted at the end of a transmission line and the incident and reflected pulse is observed. In this way the sample resistance is compared with the known impedance of the coaxial transmission line and no current measuring series resistance is needed. Short pulse risetimes (170 psec) are obtained and difficulties which arise from the current measuring resistor, like temperature dependence and nonlinearity at high currents, do not obscure the measurements.